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  • 1
    Online Resource
    Online Resource
    Sediment and pore water chemistry of cores 214 and 755 recovered during Meteor M72/1 and Poseidon POS317/2 cruise, northwestern Black Sea, supplementary data to: Henkel, Susann; Mogollón, José M; Nöthen, Kerstin; Franke, Christine; Bogus, Kara; Robin, Eric; Bahr, André; Blumenberg, Martin; Pape, Thomas; Seifert, Richard; März, Christian; de Lange, Gert Jan; Kasten, Sabine (2012): Diagenetic barium cycling in Black Sea sediments - A case study for anoxic marine environments. Geochimica et Cosmochimica Acta, 88, 88-105 (2012)
    Details Availability
    Keywords: Datensammlung
    Description / Table of Contents: High-resolution sedimentary records of major and minor elements (Al, Ba, Ca, Sr, Ti), total organic carbon (TOC), and profiles of pore water constituents (SO42-, CH4, Ca2+, Ba2+, Mg2+, alkalinity) were obtained for two gravity cores (core 755, 501 m water depth and core 214, 1686 m water depth) from the northwestern Black Sea. The records were examined in order to gain insight into the cycling of Ba in anoxic marine sediments characterized by a shallow sulfate-methane transition (SMT) as well as the applicability of barite as a primary productivity proxy in such a setting. The Ba records are strongly overprinted by diagenetic barite (BaSO4) precipitation and remobilization; authigenic Ba enrichments were found at both sites at and slightly above the current SMT. Transport reaction modeling was applied to simulate the migration of the SMT during the changing geochemical conditions after the Holocene seawater intrusion into the Black Sea. Based on this, sediment intervals affected by diagenetic Ba redistribution were identified. Results reveal that the intense overprint of Ba and Baxs (Ba excess above detrital average) strongly limits its correlation to primary productivity. These findings have implications for other modern and ancient anoxic basins, such as sections covering the Oceanic Anoxic Events for which Ba is frequently used as a primary productivity indicator. Our study also demonstrates the limitations concerning the use of Baxs as a tracer for downward migrations of the SMT: due to high sedimentation rates at the investigated sites, diagenetic barite fronts are buried below the SMT within a relatively short period. Thus, 'relict' barite fronts would only be preserved for a few thousands of years, if at all.〈br〉〈br〉REFERENCE:〈br〉Blumenberg, Martin; Seifert, Richard; Kasten, Sabine; Bahlmann, E; Michaelis, Walter (2009): Euphotic zone bacterioplankton sources major bacteriohopanepolyols in the Holocene Black Sea. Geochimica et Cosmochimica Acta, 73(3), 750-766
    Type of Medium: Online Resource
    Pages: 4 Datasets , Format: application/zip
    URL: http://dx.doi.org/10.1594/PANGAEA.779906
    URL: http://nbn-resolving.de/urn:nbn:de:tib-10.1594/PANGAEA.7799063
    URN: urn:nbn:de:tib-10.1594/PANGAEA.7799063
    DOI: 10.1594/PANGAEA.779906
    Language: English
    Note: This dataset is supplement to doi:10.1016/j.gca.2012.04.021 , This dataset is cited by doi:10.1016/j.gca.2008.11.005
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  • 2
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    Ecosystem changes through the Permian–Triassic and Triassic–Jurassic critical intervals: Evidence from sedimentology, palaeontology and geochemistry (2023)
    Details
    Publication Date: 2024-02-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉ABSTRACT〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Permian–Triassic and Triassic–Jurassic critical intervals are among the most significant ecological upheavals in the Phanerozoic. Both evolutionary junctures are characterized by environmental deterioration associated with a marked biodiversity decline. In this study, Permian–Triassic and Triassic–Jurassic boundary sections from South China and the Northern Calcareous Alps were investigated. In order to reconstruct the interplay between biotic and abiotic processes, a multifaceted approach that included optical microscopy, X‐ray diffraction, Raman spectroscopy, stable carbon isotopes and lipid biomarkers was employed. The lower parts of these two sections are similar as both consist of limestone with abundant fossils of eukaryotic organisms. However, the Permian–Triassic record is dominated by dasyclad green algae and fusulinid foraminifera, while the Triassic–Jurassic record is typified by corals and coralline sponges. Moving upward, both sections consist mainly of micrite and marl. Concerning the Permian–Triassic section, it transits to volcanic ash intercalated by a distinct limestone bed with abundant calcispheres (tentatively attributed to ancestors of dinoflagellates). The Triassic–Jurassic section does not provide direct evidence for volcanic activity, but also becomes rich in calcisphere‐type cysts towards the top. Additionally, the section preserves abundant 4‐methyl sterenes (diagnostic for dinoflagellates) and C〈sub〉37–39〈/sub〉 〈italic toggle="no"〉n〈/italic〉‐alkanes (indicative for haptophytes). Hence, both critical intervals were associated with marked blooms of (ancestral) dinoflagellates and haptophytes (for example, coccolithophorids). These blooms were followed by ecological lag‐phases, as indicated by low carbonate contents and scarce fossils which only increased further up the sections. For both critical intervals, it is commonly assumed that the formation of voluminous volcanic provinces (Siberian Traps and Central Atlantic Magmatic Province, respectively), as well as associated processes (for example, burning of organic‐rich sediments such as coal), resulted in ecological devastation. However, results suggest that volcanism also had a positive effect on certain planktonic primary producers such as dinoflagellates and haptophytes, perhaps by delivering essential nutrients.〈/p〉
    Description: China Council Scholarship
    Description: Teach@Tübingen Fellowship
    Keywords: ddc:560 ; Calcispheres ; dinoflagellates ; haptophytes ; lipid biomarkers ; mass extinctions ; microfacies ; stable carbon isotopes
    Language: English
    Type: doc-type:article
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  • 3
    Electronic Resource
    Electronic Resource
    Anaerobic oxidation of short-chain hydrocarbons by marine sulphate-reducing bacteria (2007)
    [s.l.] : Nature Publishing Group
    Nature 449 (2007), S. 898-901 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The short-chain hydrocarbons ethane, propane and butane are constituents of natural gas. They are usually assumed to be of thermochemical origin, but biological formation of ethane and propane has been also observed. Microbial utilization of short-chain hydrocarbons has been shown in some ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature06200
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  • 4
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    Methane dynamics in a microbial community of the Black Sea traced by stable carbon isotopes in vitro (2006)
    Elsevier
    In:  Organic Geochemistry, 37 (10). pp. 1411-1419.
    Details
    Publication Date: 2017-06-27
    Description: There is growing concern about the transfer of methane originating from water bodies to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles or indirectly via vertical turbulent transport. This work quantifies methane gas bubble dissolution using a combination of bubble modeling and acoustic observations of rising bubbles to determine what fraction of the methane transported by bubbles will reach the atmosphere. The bubble model predicts the evolving bubble size, gas composition, and rise distance and is suitable for almost all aquatic environments. The model was validated using methane and argon bubble dissolution measurements obtained from the literature for deep, oxic, saline water with excellent results. Methane bubbles from within the hydrate stability zone (typically below 500 m water depth in the ocean) are believed to form an outer hydrate rim. To explain the subsequent slow dissolution, a model calibration was performed using bubble dissolution data from the literature measured within the hydrate stability zone. The calibrated model explains the impressively tall flares (〉1300 m) observed in the hydrate stability zone of the Black Sea. This study suggests that only a small amount of methane reaches the surface at active seep sites in the Black Sea, and this only from very shallow water areas (〈100 m). Clearly, the Black Sea and the ocean are rather effective barriers against the transfer of bubble methane to the atmosphere, although substantial amounts of methane may reach the surface in shallow lakes and reservoirs.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.orggeochem.2006.03.007
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  • 5
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    High occurrences of brominated lipid fatty acids in boreal sponges of the order Halichondrida (2007)
    Springer
    In:  Marine Biology, 150 (6). pp. 1153-1160.
    Details
    Publication Date: 2017-06-27
    Description: Sponges of warm- and temperate- but also cold-waters are known to synthesize structurally diverse primary and secondary metabolites. These compounds fulfill a variety of functions including adaptations of the cell membranes to environmental conditions. We show here that boreal sponges of the order Halichondrida are rich sources of brominated lipid fatty acids. The comparison of lipid compositions of halichondrid Demospongiae from boreal and warmer waters indicates an accumulation of brominated fatty acids in sponges from colder settings. Moreover, the spatial distribution of brominated fatty acids in the sponge tissue of one widely distributed sponge of the North-East Atlantic (Phakellia ventilabrum) hints to a function related to membrane fluidity and permeability rather than to defense against predation. However, brominated fatty acids are diagnostic for the presence of bromoperoxidases in sponges and may therefore be potentially useful as markers in a chemical screening for secondary metabolites of pharmacological interest.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-006-0445-7
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  • 6
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    Biosynthesis of hopanoids by sulfate-reducing bacteria (genus Desulfovibrio) (2006)
    Wiley / Society for Applied Microbiology and Blackwell Publishing Ltd,
    In:  Environmental Microbiology, 8 (7). pp. 1220-1227.
    Details
    Publication Date: 2017-06-28
    Description: Sulfate reduction accounts for about a half of the remineralization of organic carbon in anoxic marine shelf regions. Moreover, it was already a major microbial process in the very early ocean at least 2.4 billion years before the present. Here we demonstrate for the first time the capability of sulfate-reducing bacteria (SRB) to biosynthesize hopanoids, compounds that are quantitatively important and widely distributed biomarkers in recent and fossil sediments dating back to the late Archean. We found high concentrations (9.8–12.3 mg per gram of dry cells) of non-extended and extended bacteriohopanoids (bacteriohopanetetrol, aminobacteriohopanetriol, aminobacteriohopanetetrol) in pure cultures of SRB belonging to the widely distributed genus Desulfovibrio. Biohopanoids were found – considered as membrane rigidifiers – in more than 50% of bacterial species analysed so far. However, their biosynthesis appeared to be restricted to aerobes or facultative anaerobes with a very few recently described exceptions. Consequently, findings of sedimentary hopanoids are often used as indication for oxygenated settings. Nevertheless, our findings shed new light on the presence of hopanoids in specific anoxic settings and suggests that SRB are substantial sources of this quantitatively important lipid class in recent but also past anoxic environments.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/j.1462-2920.2006.01014.x
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  • 7
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    Unexpected occurrence of hopanoids at gas seeps in the Black Sea (2003)
    Elsevier
    In:  Organic Geochemistry, 34 (1). pp. 81-87.
    Details
    Publication Date: 2017-06-28
    Description: High concentrations of free C32 bis-homohopanoic acids (up to 433 μg/g dry wt) occur in microbial mats at methane seeps in anoxic Black Sea waters. These compounds show a strong preference for the ‘geological’ 17α(H),21β(H)- over the ‘biological’ 17β(H),21β(H)-configuration (αβ/ββ ratios up to 30.7) and indicate the potential formation of αβ-hopanoids in modern environments. Strong 13C-depletions (δ13C as low as −78.4‰ PDB) indicate an in situ generation of these hopanoids by biota involved in the anaerobic cycling of methane carbon. The inferred presence of hopanoids indigenous to a permanently anoxic marine environment is significant because these lipids are not known to occur in strictly anaerobic bacteria.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0146-6380(02)00191-2
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  • 8
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    A novel, multi-layered methanotrophic microbial mat system growing on the sediment of the Black Sea (2008)
    Wiley / Society for Applied Microbiology and Blackwell Publishing Ltd,
    In:  Environmental Microbiology, 10 (8). pp. 1934-1947.
    Details
    Publication Date: 2017-06-27
    Description: A novel microbially diverse type of 1- to 5-cm-thick mat performing anaerobic oxidation of methane (AOM) and covering several square metres of the seafloor was discovered in the Black Sea at 180 m water depth. Contrary to other AOM-mat systems of the Black Sea these floating mats are not associated to free gas and are not stabilized by authigenic carbonates. However, supply of methane is ensured by the horizontal orientation of the mats acting as a cover of methane enriched fluids ascending from the underlying sediments. Thorough investigation of their community composition by molecular microbiology and lipid biomarkers, metabolic activities and elemental composition showed that the mats provide a clearly structured system with extracellular polymeric substances (EPS) building the framework of the mats. The top black zone, showing high rates of AOM (15 μmol gdw−1 day−1), was dominated by ANME-2, while the following equally active pink layer was dominated by ANME-1 Archaea. The lowest AOM activity (2 μmol gdw−1 day−1) and cell numbers were found in the greyish middle part delimited towards the sediment by a second pink, ANME-1-dominated and sometimes a black outer layer (ANME-2). Our work clearly shows that the different microbial populations are established along defined chemical gradients such as methane, sulfate or sulfide.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/j.1462-2920.2008.01607.x
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  • 9
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    Lipid geochemistry of methane-seep-related Black Sea carbonates (2005)
    Elsevier
    In:  Palaeogeography Palaeoclimatology Palaeoecology, 227 (1-3). pp. 31-47.
    Details
    Publication Date: 2017-06-30
    Description: Carbonates recovered from anoxic waters between 235 and 1555 m depth in the northwestern Black Sea were analyzed for lipid biomarkers and stable carbon isotopic compositions. In addition, a methane-seep-related microbial mat and a sample of surface sediment recovered from a non-seep site were studied for comparison. High concentrations of strongly 13C-depleted lipids attributed to bacteria and archaea mediating the anaerobic oxidation of methane (AOM) were found in all samples except for the sediment. Differences of the dominant AOM-performing communities between the carbonates indicated by specific lipid patterns appear to be caused by the respective biogeochemical settings. High proportions of ANME-2 consortia are found at sites of assumingly high partial pressures of methane while ANME-1 associations dominate at locations of moderate methane supply. In the sedimentary concretion, a complex mixture of biomarkers for terrestrial and planktonic organisms was found. Different molecular structures along with strong variations in the stable carbon isotopic compositions (δ13C = − 20.2‰ to − 94.3‰) allow for an estimation of the proportions of tetraether-bound biphytanes derived from planktonic Crenarchaeota and methanotrophic Euryarchaeota. Our data imply that the shape of AOM-derived carbonate precipitates in Black Sea environments is crucially influenced by the respective methane supply. Active AOM-driven chimney-like bioherms, similar to those previously observed on the Ukrainian shelf, might also develop in the deep euxinic zone at 1555 m water depths.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.palaeo.2005.04.030
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  • 10
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    Gas hydrate decomposition recorded by authigenic barite at pockmark sites of the northern Congo Fan (2012)
    Springer
    In:  Geo-Marine Letters, 32 (5/6). pp. 515-524.
    Details
    Publication Date: 2017-05-19
    Description: The geochemical cycling of barium was investigated in sediments of pockmarks of the northern Congo Fan, characterized by surface and subsurface gas hydrates, chemosynthetic fauna, and authigenic carbonates. Two gravity cores retrieved from the so-called Hydrate Hole and Worm Hole pockmarks were examined using high-resolution pore-water and solid-phase analyses. The results indicate that, although gas hydrates in the study area are stable with respect to pressure and temperature, they are and have been subject to dissolution due to methane-undersaturated pore waters. The process significantly driving dissolution is the anaerobic oxidation of methane (AOM) above the shallowest hydrate-bearing sediment layer. It is suggested that episodic seep events temporarily increase the upward flux of methane, and induce hydrate formation close to the sediment surface. AOM establishes at a sediment depth where the upward flux of methane from the uppermost hydrate layer counterbalances the downward flux of seawater sulfate. After seepage ceases, AOM continues to consume methane at the sulfate/methane transition (SMT) above the hydrates, thereby driving the progressive dissolution of the hydrates “from above”. As a result the SMT migrates downward, leaving behind enrichments of authigenic barite and carbonates that typically precipitate at this biogeochemical reaction front. Calculation of the time needed to produce the observed solid-phase barium enrichments above the present-day depths of the SMT served to track the net downward migration of the SMT and to estimate the total time of hydrate dissolution in the recovered sediments. Methane fluxes were higher, and the SMT was located closer to the sediment surface in the past at both sites. Active seepage and hydrate formation are inferred to have occurred only a few thousands of years ago at the Hydrate Hole site. By contrast, AOM-driven hydrate dissolution as a consequence of an overall net decrease in upward methane flux seems to have persisted for a considerably longer time at the Worm Hole site, amounting to a few tens of thousands of years.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00367-012-0288-9
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